The present invention relates to a method of balancing the output of two lines of a packing system.
The present invention may be used to advantage in the tobacco industry, particularly for forming and wrapping cartons of cigarettes, to which the following description refers purely by way of example.
The tobacco industry is known to employ packing systems featuring two packing lines, and which comprise a two-line or dual cigarette packing machine, a cartoning machine, and a two-line or dual cellophaning machine interposed between the dual packing machine and the cartoning machine.
In normal operating conditions, the three machines of packing systems of the above type are driven synchronously so that each operates in time with the other two.
For any of various reasons, however, the operating speed of one of the machines may fall below the common speed at which the three machines are timed to operate. For example, if the packing machine slows down, even temporarily, with respect to the cellophaning and cartoning machines, each packing machine line produces one or more packets short of the number required to form a carton in at least one operating cycle of the system, i.e. in at least one cycle of operations performed simultaneously on the two lines by the three machines in the system to form and wrap two respective cartons of cigarettes, so that the cartoning machine produces at least two cartons with one or more packets missing.
Moreover, at least one reject station for rejecting faulty packets is normally provided along each of the two lines in the system.
Rejections obviously have the effect of unbalancing the lines. For example, in the event the packing machine produces a faulty packet on one line, the faulty packet is later rejected at the reject station, so that the number of packets supplied to the cellophaning machine on that particular line is one packet short, and, in the corresponding operating cycle, the cartoning machine produces two cartons, one of which with one packet short.
The above drawbacks could be eliminated by compensating the output of the two lines in the packing system by means of compensating stores interposed, along each of the two lines, between the packing and cellophaning machines, and between the cellophaning and cartoning machines. Such a solution, however, though valid, is fairly expensive.